1. Field of the Invention
The present invention is related to phacoemulsification needles used in ophthalmic surgery and more specifically, to sleeves which surround the phacoemulsification needle during surgery.
2. Description of Related Art
It is well known to remove cataracts from a patient's eyes and replace the removed cataract affected lens with an artificial intraocular lens. It is common and accepted practice to remove the cataract affected lens via phacoemulsification.
Phacoemulsification enables the lens to be removed from the eye through a very small incision, typically on the order of 3 mm. Phacoemulsification involves using high frequency ultrasound energy transmitted through a handpiece into a phacoemulsification needle to fragment the affected lens. Once the lens is fragmented or emulsified, the lens material is aspirated along with irrigation fluid through a lumen of the phacoemulsification needle, and through the handpiece and into a collection reservoir of a surgical system.
During aspiration of the lens material it is typical to simultaneously insert a flow of irrigation fluid into the eye. This flow is provided to prevent the eye from collapsing during aspiration. It is also typical that a phacoemulsification needle provides what is commonly referred to as coaxial irrigation. This coaxial irrigation provides the flow of irrigation fluid into the eye via a resilient sleeve surrounding the needle. The irrigation sleeve typically includes irrigation ports at the distal end of the sleeve so that fluid flows from the handpiece in between the sleeve and the outside of the needle. While phacoemulsification and coaxial irrigation has proven to be very successful and safe, there is a strong desire to reduce the incision size even further from the current average incision of 3 mm. One procedure being adopted to accomplish this is a technique known as bi-manual cataract extraction. In bi-manual extraction, there are typically at least two very small incisions made on the order of 1.4 mm in length. In order to accommodate such a small size, the irrigation portion with a separate irrigation cannula is inserted through one incision and a phaco needle with only aspiration and typically no sleeve is inserted through the other incision.
In bi-manual surgery, without the insulative and sealing effects of an outer sleeve around the aspiration needle, there are concerns regarding excessive heating of the corneal tissue due to the vibration of the needle and also fluid leakage around the needle at the incision site.
Therefore, it would advantageous and desirable to have a phacoemulsification needle that provides the insulative and sealing properties of the prior art coaxial phaco needle with a sleeve, without requiring a larger incision size to accommodate the sleeve.